Notification of string changes

Author: Damyon Wiese
MDL-31414: Separate settings to control notifications for submissions, late submissions and submission receipts
This adds separate controls for the sending of notifications from the mod_assign.

The separate notifications are: student submission receipt (for students), feedback available (for students)
and submission updated (for graders). The grader notifications can be enabled for all submissions or just late ones.

Added code to reset the message providers on upgrade (only applies for a 2.3 dev version)


http://git.moodle.org/gw?p=moodle.git;a=commit;h=75f87a57956fd4168929908d5dc428c84d6b8b3d
http://github.com/moodle/moodle/commit/75f87a57956fd4168929908d5dc428c84d6b8b3d

+ 2.3 en [gradersubmissionupdatedtext,mod_assign]
+ 2.3 en [gradersubmissionupdatedhtml,mod_assign]
+ 2.3 en [gradersubmissionupdatedsmall,mod_assign]
+ 2.3 en [feedbackavailabletext,mod_assign]
+ 2.3 en [feedbackavailablehtml,mod_assign]
+ 2.3 en [feedbackavailablesmall,mod_assign]
+ 2.3 en [feedbackpluginforgradebook_help,mod_assign]
+ 2.3 en [messageprovider:assign_student_notification,mod_assign]
+ 2.3 en [messageprovider:assign_grader_notification,mod_assign]
+ 2.3 en [notification,mod_assign]
+ 2.3 en [sendnotifications,mod_assign]
+ 2.3 en [sendlatenotifications,mod_assign]
+ 2.3 en [sendlatenotifications_help,mod_assign]
+ 2.3 en [sendsubmissionreceipts,mod_assign]
+ 2.3 en [sendsubmissionreceipts_help,mod_assign]
+ 2.3 en [submissionreceipttext,mod_assign]
+ 2.3 en [submissionreceipthtml,mod_assign]
+ 2.3 en [submissionreceiptsmall,mod_assign]
- 2.3 en [emailgradermail,mod_assign]
- 2.3 en [emailgradermailhtml,mod_assign]
- 2.3 en [feedbackcomments,mod_assign]
- 2.3 en [messageprovider:assign_updates,mod_assign]